// Connection.h

// Interfaces to the cConnection class representing a single pair of connected sockets





#pragma once

#include "ByteBuffer.h"
#include "mbedTLS++/AesCfb128Decryptor.h"
#include "mbedTLS++/AesCfb128Encryptor.h"

#ifndef _WIN32
	typedef int SOCKET;
#endif





class cServer;





class cConnection
{
	/** Base for the log filename and all files connected to this log */
	AString m_LogNameBase;

	/** Index for the next file into which item metadata should be written (ParseSlot() function) */
	int m_ItemIdx;

	cCriticalSection m_CSLog;
	FILE * m_LogFile;

	cServer & m_Server;
	SOCKET m_ClientSocket;
	SOCKET m_ServerSocket;

	std::chrono::steady_clock::time_point m_BeginTick;  // Tick when the relative time was first retrieved (used for GetRelativeTime())

	enum eConnectionState
	{
		csUnencrypted,           // The connection is not encrypted. Packets must be decoded in order to be able to start decryption.
		csEncryptedUnderstood,   // The communication is encrypted and so far all packets have been understood, so they can be still decoded
		csEncryptedUnknown,      // The communication is encrypted, but an unknown packet has been received, so packets cannot be decoded anymore
		csWaitingForEncryption,  // The communication is waiting for the other line to establish encryption
	};

	eConnectionState m_ClientState;
	eConnectionState m_ServerState;

	int m_Nonce;

public:
	cConnection(SOCKET a_ClientSocket, cServer & a_Server);
	~cConnection();

	void Run(void);

	void vLog(const char * a_Format, fmt::printf_args a_ArgList);

	template <typename... Args>
	void Log(const char * a_Format, const Args & ... a_Args)
	{
		vLog(a_Format, fmt::make_printf_args(a_Args...));
	}

	void vDataLog(const void * a_Data, size_t a_Size, const char * a_Format, fmt::printf_args a_ArgList);

	template <typename... Args>
	void DataLog(const void * a_Data, size_t a_Size, const char * a_Format, const Args & ... a_Args)
	{
		vDataLog(a_Data, a_Size, a_Format, fmt::make_printf_args(a_Args...));
	}

	void LogFlush(void);

protected:

	cByteBuffer m_ClientBuffer;
	cByteBuffer m_ServerBuffer;

	cAesCfb128Decryptor m_ServerDecryptor;
	cAesCfb128Encryptor m_ServerEncryptor;

	ContiguousByteBuffer m_ServerEncryptionBuffer;  // Buffer for the data to be sent to the server once encryption is established

	/** Set to true when PACKET_PING is received from the client; will cause special parsing for server kick */
	bool m_HasClientPinged;

	/*
	The protocol states can be one of:
	-1: no initial handshake received yet
	1: status
	2: login
	3: game
	*/
	/** State the to-server protocol is in (as defined by the initial handshake / login), -1 if no initial handshake received yet */
	int m_ServerProtocolState;

	/** State the to-client protocol is in (as defined by the initial handshake / login), -1 if no initial handshake received yet */
	int m_ClientProtocolState;

	/** True if the server connection has provided encryption keys */
	bool m_IsServerEncrypted;


	bool ConnectToServer(void);

	/** Relays data from server to client; returns false if connection aborted */
	bool RelayFromServer(void);

	/** Relays data from client to server; returns false if connection aborted */
	bool RelayFromClient(void);

	/** Returns the time relative to the first call of this function, in the fractional seconds elapsed */
	double GetRelativeTime(void);

	/** Sends data to the specified socket. If sending fails, prints a fail message using a_Peer and returns false. */
	bool SendData(SOCKET a_Socket, ContiguousByteBufferView a_Data, const char * a_Peer);

	/** Sends data to the specified socket. If sending fails, prints a fail message using a_Peer and returns false. */
	bool SendData(SOCKET a_Socket, cByteBuffer & a_Data, const char * a_Peer);

	/** Sends data to the specfied socket, after encrypting it using a_Encryptor. If sending fails, prints a fail message using a_Peer and returns false */
	bool SendEncryptedData(SOCKET a_Socket, cAesCfb128Encryptor & a_Encryptor, ContiguousByteBuffer & a_Data, const char * a_Peer);

	/** Sends data to the specfied socket, after encrypting it using a_Encryptor. If sending fails, prints a fail message using a_Peer and returns false */
	bool SendEncryptedData(SOCKET a_Socket, cAesCfb128Encryptor & a_Encryptor, cByteBuffer & a_Data, const char * a_Peer);

	/** Decodes packets coming from the client, sends appropriate counterparts to the server; returns false if the connection is to be dropped */
	bool DecodeClientsPackets(const char * a_Data, int a_Size);

	/** Decodes packets coming from the server, sends appropriate counterparts to the client; returns false if the connection is to be dropped */
	bool DecodeServersPackets(const char * a_Data, int a_Size);

	// Packet handling, client-side, initial:
	bool HandleClientHandshake(void);

	// Packet handling, client-side, status:
	bool HandleClientStatusPing(void);
	bool HandleClientStatusRequest(void);

	// Packet handling, client-side, login:
	bool HandleClientLoginEncryptionKeyResponse(void);
	bool HandleClientLoginStart(void);

	// Packet handling, client-side, game:
	bool HandleClientAnimation(void);
	bool HandleClientBlockDig(void);
	bool HandleClientBlockPlace(void);
	bool HandleClientChatMessage(void);
	bool HandleClientClientStatuses(void);
	bool HandleClientCreativeInventoryAction(void);
	bool HandleClientDisconnect(void);
	bool HandleClientEntityAction(void);
	bool HandleClientKeepAlive(void);
	bool HandleClientLocaleAndView(void);
	bool HandleClientPing(void);
	bool HandleClientPlayerAbilities(void);
	bool HandleClientPlayerLook(void);
	bool HandleClientPlayerOnGround(void);
	bool HandleClientPlayerPosition(void);
	bool HandleClientPlayerPositionLook(void);
	bool HandleClientPluginMessage(void);
	bool HandleClientSlotSelect(void);
	bool HandleClientTabCompletion(void);
	bool HandleClientUpdateSign(void);
	bool HandleClientUseEntity(void);
	bool HandleClientWindowClick(void);
	bool HandleClientWindowClose(void);

	bool HandleClientUnknownPacket(UInt32 a_PacketType, UInt32 a_PacketLen, UInt32 a_PacketReadSoFar);

	// Packet handling, server-side, login:
	bool HandleServerLoginDisconnect(void);
	bool HandleServerLoginEncryptionKeyRequest(void);
	bool HandleServerLoginSuccess(void);

	// Packet handling, server-side, game:
	bool HandleServerAttachEntity(void);
	bool HandleServerBlockAction(void);
	bool HandleServerBlockChange(void);
	bool HandleServerChangeGameState(void);
	bool HandleServerChatMessage(void);
	bool HandleServerCollectPickup(void);
	bool HandleServerCompass(void);
	bool HandleServerDestroyEntities(void);
	bool HandleServerEntity(void);
	bool HandleServerEntityEquipment(void);
	bool HandleServerEntityHeadLook(void);
	bool HandleServerEntityLook(void);
	bool HandleServerEntityMetadata(void);
	bool HandleServerEntityProperties(void);
	bool HandleServerEntityRelativeMove(void);
	bool HandleServerEntityRelativeMoveLook(void);
	bool HandleServerEntityStatus(void);
	bool HandleServerEntityTeleport(void);
	bool HandleServerEntityVelocity(void);
	bool HandleServerExplosion(void);
	bool HandleServerIncrementStatistic(void);
	bool HandleServerJoinGame(void);
	bool HandleServerKeepAlive(void);
	bool HandleServerKick(void);
	bool HandleServerLogin(void);
	bool HandleServerMapChunk(void);
	bool HandleServerMapChunkBulk(void);
	bool HandleServerMultiBlockChange(void);
	bool HandleServerNamedSoundEffect(void);
	bool HandleServerPlayerAbilities(void);
	bool HandleServerPlayerAnimation(void);
	bool HandleServerPlayerListItem(void);
	bool HandleServerPlayerPositionLook(void);
	bool HandleServerPluginMessage(void);
	bool HandleServerRespawn(void);
	bool HandleServerSetExperience(void);
	bool HandleServerSetSlot(void);
	bool HandleServerSlotSelect(void);
	bool HandleServerSoundEffect(void);
	bool HandleServerSpawnExperienceOrbs(void);
	bool HandleServerSpawnMob(void);
	bool HandleServerSpawnNamedEntity(void);
	bool HandleServerSpawnObjectVehicle(void);
	bool HandleServerSpawnPainting(void);
	bool HandleServerSpawnPickup(void);
	bool HandleServerStatistics(void);
	bool HandleServerStatusPing(void);
	bool HandleServerStatusResponse(void);
	bool HandleServerTabCompletion(void);
	bool HandleServerTimeUpdate(void);
	bool HandleServerUpdateHealth(void);
	bool HandleServerUpdateSign(void);
	bool HandleServerUpdateTileEntity(void);
	bool HandleServerUseBed(void);
	bool HandleServerWindowClose(void);
	bool HandleServerWindowContents(void);
	bool HandleServerWindowOpen(void);

	bool HandleServerUnknownPacket(UInt32 a_PacketType, UInt32 a_PacketLen, UInt32 a_PacketReadSoFar);

	/** Parses the slot data in a_Buffer into item description; returns true if successful, false if not enough data */
	bool ParseSlot(cByteBuffer & a_Buffer, AString & a_ItemDesc);

	/** Parses the metadata in a_Buffer into raw metadata in an AString; returns true if successful, false if not enough data */
	bool ParseMetadata(cByteBuffer & a_Buffer, AString & a_Metadata);

	/** Logs the contents of the metadata in the AString, using Log(). Assumes a_Metadata is valid (parsed by ParseMetadata()). The log is indented by a_IndentCount spaces */
	void LogMetadata(const AString & a_Metadata, size_t a_IndentCount);

	/** Send EKResp to the server: */
	void SendEncryptionKeyResponse(const AString & a_ServerPublicKey, const AString & a_Nonce);

	/** Starts client encryption based on the parameters received */
	void StartClientEncryption(const AString & a_EncryptedSecret, const AString & a_EncryptedNonce);
} ;